The present invention relates, in general, to a method for improving a drainage of aqueous humor within the eye of a living being, and to a device for widening the circular canal of Schlemm to improve drainage of aqueous humor.
If the trabecular meshwork is either partially or completely non-functional due to an obstruction or back-up, or pathological changes, natural flow of the aqueous humor becomes limited, thereby raising the pressure inside the eye which negatively impacts on the blood circulation and the function of the visual nerve. The resulting disease is commonly known under the name xe2x80x9cglaucomaxe2x80x9d which may lead to blindness in the eye.
U.S. Pat. Nos. 5,360,399 and 5,486,165 describe a method and apparatus, by which the trabecular meshwork, which is located upstream of the canal of Schlemm and which due to pathological changes, may either partially or completely obstruct the outflow of aqueous humor, is essentially widened by the hydraulic pressure of a highly viscous aqueous solution, which when injected into the canal of Schlemm opens it at several location points, so that an outflow of the aqueous humor can be realized.
Surgical methods are known for increasing the flow of aqueous humor within the eye, in particular, when the outflow of the aqueous humor is diminished. However, surgical methods which open the canal of Schlemm and the trabecular meshwork have not necessarily led to the required success in the long term because, for example, regeneration of the tissue closes the openings in the trabecular meshworks.
It is thus an object of the present invention to provide an improved method for realizing an enhanced flow of aqueous humor within the eye, obviating the afore-stated drawbacks.
In particular, it is an object of the present invention to provide an improved method by which the necessary drainage of the aqueous humor via the outflow pathways of the eye is realized and which thereby results in an improved circulation of the aqueous humor in the eye and thus regulating the pressure within the eye.
These objects, and others which will become apparent hereinafter, are attained by a method in accordance with the present invention which includes the following steps: incising a first lamellar section of the sclera to form a first scleral flap; lifting the first scleral flap upwards in the direction of the cornea, thereby creating a recess in the sclera; incising a second lamellar section in the area of the recess to thereby form a second scleral flap and a support surface bounding the scleral flap; lifting the second scleral flap upwards in the direction of the first sclera flap, thereby exposing two opposite openings into the Schlemm""s canal; injecting an expanding medium through the openings into the Schlemm""s canal; folding the first scleral flap back, after severance of the second scleral flap, for placement upon the support surface, thereby confining a subscleral space adjacent the first scleral flap; injecting a viscous medium into the subscleral space; and rejoining the first scleral flap to the sclera.
In accordance with a further feature of the present invention, a slit-like passageway is formed between the subscleral space and the anterior chamber by applying a pressure force against a peripheral edge of the aqueous humor-permeable Descemet""s membrane to detach the Descemet""s membrane from the cornea. In this manner, the aqueous humor, which normally flows into the canal of Schlemm via the trabecular meshwork, flows additionally by way of Descemet""s membrane from the anterior chamber in fluid connection therewith, and the slit-like passageway, into the subscleral chamber.
According to another feature of the present invention, severance of the second scleral flap can be executed at any time after lifting the second scleral flap and before folding back the first scleral flap, i.e. before or after injection of expanding medium into the canal of Schlemm or before or after detachment of the Descemet""s membrane.
It is a further object of the present invention to provide an improved device for expanding a surgically exposed Schlemm""s canal in an eye to thereby realize an enhanced flow of aqueous humor.
This object is attained in accordance with the present invention by providing a probe insertable into the Schlemm""s canal for injecting a viscous medium to thereby generate a localized pressure buildup, with the probe having an outlet port which is defined by a diameter and an axial length, whereby the length is sized at least twice the diameter of the outlet port.
The probe is suitably connected to a pressure source for supply of expanding medium via an adapter and includes a tube which is connected to the adapter and has a circular ring shaped or elliptic cross section. The adapter may have an arcuate configuration, and the tube may have an inner axial bore which forms the outlet port and is in fluid communication with an interior space of the adapter for conduction of the expanding medium to the Schlemm""s canal. Alternatively, the tube may have an outer periphery formed with an axial groove which forms the outlet port and is in fluid communication with an interior space of the adapter for conduction of the expanding medium to the Schlemm""s canal.
According to another embodiment of the present invention, the adapter may have a T-shaped configuration and include a vertical portion and a horizontal portion formed integrally with the vertical portion for attachment of two of probes in opposite disposition, wherein each of the probes has an inner axial bore which forms part of the outlet port and is in fluid communication with an inlet port in the vertical portion of the adapter. The vertical portion is suitably connected to the pressure source via a feed conduit such that expanding medium is injected into the Schlemm""s canal via the inner axial bore of both probes simultaneously or sequentially.
According to still another feature of the present invention, the probe has a distal end and a proximal end and includes a transition piece which is secured to the proximal end of the probe for attachment to the adapter, with the transition piece having a conical configuration or a circular arc shaped configuration.
The probe may be formed in one piece with the adapter, or the probe may be securely fixed in a complementary recess of the adapter. Suitably, the probe is made of flexible plastic material, e.g. transparent plastic, or may be made of a metal tube or, a flexible tube from metal, e.g. a nickel titanium alloy.